Emergency services were called to Burlish Top Nature Reserve, off Kingsway, in Stourport, shortly after 1pm today, to reports of a cyclist coming off his bike.
A male teenager, aged 17, was found to be in a serious condition, before being taken to hospital by the Midlands Air Ambulance.
A spokesman from West Midlands Ambulance Service said: "We were called at 1:07pm on Monday to reports a cyclist had come off their bike at Burlish Top Nature Reserve.
"We sent the Midlands Air Ambulance from Cosford, two land ambulances, a paramedic officer and BASICS doctor to the scene.
"On arrival we found one patient, a teenage male, in a serious condition.
"He was given trauma care on scene before being taken to Queen Elizabeth Hospital in Birmingham by air ambulance.”
A West Mercia Police spokesman said: "We received a call at 1.40pm today [Monday] to Torridon Close, Stourport, near to Burlish Top Nature Reserve, to a report of a 17-year-old falling of his bike.
"Officers closed the road whilst the ambulance service treated the patient."